Device for mechanical recording



April 18, 1939. R. VERMEULEN Er An.. f 29154589 DEVICE FOR MECHANICALiRECORDING Fiied Jan. 9, 1956 mvmwmzms ffm Patented Apr. 18, 1939 DEVICE FOR MECHANICAL RECORDING Roelof Vermeulen and Cornelis van Over-eem, Eindhoven, Netherlands, assignors to N. V.

Philips Netherlands Gloeilampenfabrieken,

Eindhoven,

Application January 9, 1936, Serial No. 58,435 In Germany January 25, 1935 1 Claim.

Our invention relates to'a device for mechanical recording oscillations, particularly sound vibrations, on a lm. Our invention is particularly advantageous in connection with mechanical 5 recording systemsin which a recording member is vibrated normally or substantially normally to the surface of a film to produce therein an optically-reproducible track whose Width variations are an enlargement of corresponding depth variations.

For this purpose it is known to use a recording tool having a V-shaped cutting edge enclosing an angle of about 174, which tool cuts through an opaque top-layer into a transparent recording layer which is preferably applied to a likewise transparent carrying layer. The track sc produced has width variations which are about 40 times larger than the depths variations whereby oscillations of small amplitudes, more particularly those of the higher frequencies, can also be recorded in a satisfactory manner.

In such recording the maximum enlargement is about 40 times, and if the track has amaximum Width of about 2 millimeters, the maximum cutting depth will be about 50e, the average cutting depth will be about 25a, and the width of the chisel about 2.5 millimeters. There will be a high cutting resistance in recording such a track which will tend to move the lrn with respect to the member driving same.

To eliminate this drawback the film is usually moved past the recording point by a cogged driving drum, and the recording takes place either on this drum-or by means of a special device.

' According to the U. S. Patent #2,063,560 to Willem Six the inuence of the thickness variations of the film is eliminated by moving the film in the vicinity of the recording point over a support located on the side of the recording member.

The surface of the film in which the record is formed is in contact with me support, and the film is pressed against the support with a force exceeding the force exerted on the film by the recording member.

With the use of such devices, the cogs of the driving drum are a source of trouble as they do not exactly correspond to socket holes with the result that tie film is periodically displaced on the drum.

According to the invention, the above difiiculties are eliminated'by moving the film, at the point of recording or in the neighbourhood thereof, by means of a smooth (uncogged) drum provided with an unyielding surface and driven by a driving mechanism so as to rotate at a substantially constant speed. Furthermore we provide at least at the point at which the film leaves the drum, a pressing roller whichfpresses the film against the drum with a force of preferably about 1000 grams. The surface of the pressing roller should preferably be not smooth but ymay be provided with a coating of a material such as rubber, to increase friction between the surface of the roller and the film. n

A pressing roller may also be provided on the side at which the film engages the drum. However, if the recording operation takes place at the point at which the driving drum is situated, it is sufiicient to have the required pressure between the film and the drum exerted by the recording member, 'which is mounted in this case as close as possible to the point at which the filml first comes into contact with the driving drum.

We have found that the vinvention eliminates not only the harmful influence of the cog frequency but also the danger of slippage between the roller and the film, in spite of the fact that it was believed necessary to use a cogged driving drum when the lm was loaded to such an extent.

The invention renders it possible tov ensure with the aid of simple means a faultless mechanical sound recording by means of a smooth roller, which has not been possible up to now in any way.

We are aware that in the optical recording and reproducing of sound vibrations, it has been proposed to eliminate the disadvantages of cogged driving drums by using a smooth-faced driving drum. Furthermore, it has been proposed to use a smooth-faced driving drum in mechanical recording and to hold the lm against the drum by means of suction or by magnetic force, or by pressing the illm against the drum with a cap member having a surface corresponding to the surface of the drum; however such means have been complicated and ineifective especially .in mechanical recording of the above-mentioned type.

In the device according to the invention the recording member need not be mounted so that the recording takes place on the driving drum, but it is also possible to mount before the driving drum, viewed in the direction of travel of the film, a device as described in the above-mentioned patent in which the recording operation takes place.

Not only the cogs of the film rollers but also those of cog wheels, worm wheels and the like may give rise to the production of disturbing frequencies in the record. -It is therefore advisable to avoid in the drive of the smooth drum. toothed or similar gearings which produce periodical disturbances.

The invention will be explained more fully with reference to the accompanying drawing in which Figure 1 is a sectional view of a carrier and shows a recording tool cutting a track therein;

Fig. 2 is a plan view of the carrier of Fig. 1 with a mechanically-recorded track;

Fig. 3 is a diagrammatic view of a recording device according to the invention in which the recording is effected on the driving drum.

Fig. 4 is a diagrammatic View of a recording device in which the A"recording operation takes place at a point near the driving roller.

The fllm shown in Fig. 1 consists of a carrying layer I, e. g. of Celluloid, to which is applied a.

cutting layer 3 which is provided in its turn with f atop layer 2. The recording member I, which is formed as a chisel having a V-shaped cutting edge, vibrates n" the direction of the arrow, i. e.

normally to. the surface of the illm in accordance with the oscillations to be recorded. 'I'he lm travels normally to the plane of the drawing at a uniform speed whereby tool I produces an oscillation track as shown, in Figure 2. This track shows depth variations and similar width variations which are about 40 times larger than the depth variations owing to the fact that the angle between the limbs of the V-shaped cutting edge of the chisel differs only slightly from 180. As shown in Figure 1, the angle of the cutting edge is considerably less than actual size to clari fy the illustration. y

In Figure 3, reference numeral 5 denotes the driving drum which is driven at a uniform speed. A lm 6, which may be the film chown in Figure 2, is caused by drum 5 to travel to a driven cogged roller 1 via a pressing roller S mounted behind the drum in the direction of travel of the film.

The pressing roller 9 is preferably provided with a rubber sheath II). Reference numeral II indicates the recording member which may be the cutting tool of Fig. 1, whereas reference numeral I3 denotes the xed pivot of the spring-biased lever for the pressing roller.

In Figure 4. the members corresponding to those shown in the form of construction of Figure 3 are denoted by the same reference numerals. Contrary to the construction shown in Figure 3, the recording operation takes place before illm reaches the smooth drum 5. For this purpose the film passes over a cover plate I 4 backed by a compression spring I5 and is forced with the side in which the record has to be formed against a stationary support I6. Owing to this arrangement, the mutual lpositions of the fllm surface and of the recording member .I Iare completely determined and variations of the mutual positions due to variations in the thickness of the lm are completely avoided.

What we claim is:

A device for mechanically recording sound on a film comprising means for'moving the film at a substantially constant speed comprising a driving drum having a smooth cylindrical surface, said lm being in contact with a portion of said surface, recording means for producing in said film before it reaches said drum a sound track having width variations which are a proportional enlargement of the depth variations, said recording means comprising a cutting tool having a V-shaped cutting edge, a stationary member provided with an aperture for the passage of said tool. and means including a movable pressing 35 member to press the illm against said stationary member, and means to prevent slippage of lsaid lm 'upon said surface comprising a roller pressing the lm against the surface at the point at which the film leaves the surface.

CORNELIS vvan OVEREEM. 

